One type of valve used to control fluid flow in subterranean wells is known as an inflatable packer. In its simplest form a packer valve includes a pressure element adapted to sealingly engage, or disengage, a conduit of the well, such as a pipe or bore hole, to prevent, or to allow, fluid flow through the conduit. This allows a portion of a well to be isolated for sampling, flow testing, cementing, and other operations.
Inflatable packers can also include an internal mandrel configured as a conduit for pumping fluids out of the well, or for injecting fluids into the well. One application in which water is injected into a water well is known as Aquifer Storage and Recovery (ASR). Recharge water wells are used in ASR programs to assist communities during times of peak water demand. The ASR process involves injecting treated water through recharge wells into under ground aquifers during low-demand time periods, such as the winter months. The treated water can then be recovered using the recharge wells during high-demand time periods, such as the summer months.
A packer valve configured to control flow and pressure during injection of a fluid into a well is disclosed in U.S. Pat. No. 5,316,081 to Baski et al., entitled "Flow And Pressure Control Packer Valve". FIG. 1 from the above patent illustrates the prior art control valve 10 within a well 12. The control valve 10 is in fluid communication with a submersible pump 14 powered by a motor 16. In addition, the control valve 10 is in flow communication with a pump pipe 18 and with surface piping 20.
FIGS. 2A and 2B illustrate the operation of the control valve 10 during injection of water into the well 12. In FIG. 2A an inflatable element 22 of the valve 10 can be deflated to allow water injection from the surface, as indicated by flow arrows 24. The water is injected through a sand trap 28, and into an annular area 30 located between the uninflated surface of the inflatable element 22, and the inside diameter of an external housing 32 of the valve 10. The external housing 32 also includes a series of annular grooves 34 formed on the inside diameter thereof. The annular grooves 34 are configured to increase a frictional pressure loss through the valve 10 during injection, so that the injected water does not cascade and cavitate as it flows through the annular area 30 into the well 12. The annular grooves 34 can be configured to provide a desired frictional pressure loss, and thus a desired fluid pressure within the annular area 30. In addition, the inflatable element 22 can be pressurized to partially expand into the annular area 30, increasing pressure loss and reducing (controlling) flow through the valve.
In FIG. 2B, inflation of the inflatable element 22 seals the annular area 30 so that water cannot be injected into the well 12. However in this mode, water can be pumped from the well 12 through the check valve 26, and through an internal mandrel 36 of the valve 10 to the surface, as indicated by flow arrows 38.
The prior art control valve 10 is effective for controlling flow direction and fluid pressure of a fluid during injection into the well 12. However, one shortcoming of the valve 10 is that it is expensive to manufacture. In particular, the annular grooves 34 are difficult to machine on the inside diameter of the external housing 32. Typically, the grooves 34 must be machined on relatively short lengths of pipe, which must then be welded together to produce an external housing 32 with the required length.
The present invention is directed to a control valve that can also be utilized to control the flow direction and fluid pressure of a fluid during injection into a well. However, the control valve of the invention can be more easily manufactured, made with fewer parts, and is more effective in controlling fluid pressure over a wider range of well sizes than prior art control valves. The present invention is also more dependable, being much more difficult to sand lock, and not having exposed inflation tubes to break or malfunction.